PHP以表单形式发送图片

        $url="https://api.weixin.qq.com/cgi-bin/media/uploadimg?access_token=".$as;

        $file = ROOT_PATH.'public/img/logosmall.jpg';
        $obj = curl_file_create($file);
        $obj->setMimeType("image/jpeg");
        $post['buffer'] =  $obj;
        dump($post);
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_HEADER, false);
        //启用时会发送一个常规的POST请求，类型为：application/x-www-form-urlencoded，就像表单提交的一样。
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch,CURLOPT_BINARYTRANSFER,true);
        curl_setopt($ch, CURLOPT_POSTFIELDS,$post);
        curl_setopt($ch, CURLOPT_URL, $url);//上传类
        $info= curl_exec($ch);
        curl_close($ch);
        var_dump($info);